Small-Block Chevy Build - Real Cool Street Heat

We Test Some Cost-Effective Parts For Big Street Power

I have often heard it said that significant things happen in threes. I'm 90 percent sure it's coincidental, but the other 10 percent-well, not so sure. It's a Monday morning and I get a call from DSS Racing's Tom Naegele. Tom wants to know if I would like to put the latest iteration of its new line of small-block Chevy pistons through some kind of torture test. "Sure," I replied. "When I have a suitable block, I will give you a call." Later in the day I don't get one, but I do get three e-mails asking if the Zex perimeter feed plate nitrous system is any good. My response? "Don't know-haven't tried it yet."

Well, later in the day I call what is rapidly becoming my favorite core supplier, AAEQ. During my conversation with AAEQ's Eric Haugland about a late-model short-block for piston testing, the subject of porting its highly successful iron EQ23 heads crops up along with-you guessed it-its use with nitrous. Bingo-we have a plan for a street nitrous-injected 350 using DSS's new pistons, a Zex nitrous kit, and a set of ported EQ23 iron heads.

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Here is our EQ-sourced block after T&L cleaned and machined it. It's painted and ready for the rotating assembly to be installed.

After talking to all parties concerned, we decided on a basic spec and targets to shoot for. First, this was to be an honest-to-goodness street motor, not something thinly disguised as such. How honest? A steady (no lope) idle of no more than 650 rpm, plus the ability to pull right off idle in high gear. It must be capable of decent mileage and have enough oomph to push a typical automatic-equipped 3,200-pound car on slicks under the 13-second barrier without the nitrous and into the 11s through the mufflers with the nitrous.

First, the heads. The results to date with the EQ23 heads have been stellar, to say the least. The heads looked like they were very porter friendly to the extent that even a first-timer could get results. From that you might mistakenly assume they must not be that good in terms of flow to start with if even a basic porting job bumps flow up significantly. Actually, it's the other way around. Because the port shape is so good, the out-of-the-box flow is hindered to a far greater extent by minor casting flaws than would be the case for a fundamentally poor port design.

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The cost-effective T&L rotating assembly included a cast steel Scat crank. We have used these without problems at the 650 lb-ft/650hp level. All our bearing clearances were determined by micrometer measurement before assembly.

As far as the cam and valvetrain are concerned, we decided to partially bias the cam spec toward serving the engine's needs when the nitrous is in operation. A cam favoring output when the nitrous is in use needs to be on a wider lobe centerline angle and be more advanced in the engine. This meant using a cam on a 110 LCA angle instead of the 108 known to be optimal for an engine of this spec but without nitrous. This cam would be installed 6 degrees advanced instead of 4. The earlier opening of the exhaust valve allows the cylinder much needed extra time to blow down before the piston reaches BDC. This extends the useful rpm range at the top end.

Along with this, the reduced overlap resulting from the wider LCA will allow the engine to idle more slowly and smoothly. That same reduction in overlap will also improve low-speed driveability about town. All the advantages of a nitrous-biased cam spec sound good, but there are some negatives in terms of reduced torque and hp while the nitrous isn't in operation. For us, a torque reduction of some 10-15 lb-ft can be expected along with about the same in top end power. When the nitrous is on, the useable high-end rpm is 300-500 more, and the power at this higher rpm is up to 30 hp more.

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Small-Block Chevy Build - Real Cool Street Heat

Here is our EQ-sourced block after T&L cleaned and machined it. It's painted and ready for the rotating assembly to be installed.

The cost-effective T&L rotating assembly included a cast steel Scat crank. We have used these without problems at the 650 lb-ft/650hp level. All our bearing clearances were determined by micrometer measurement before assembly.

The DSS Chevy piston proved more than capable of use in a 600-plus-hp nitrous motor. Also worthy of note is the Scat rod seen here. These rods are a real race configuration; they are light, and 600 hp doesn't even faze them. For under $300, they are a steal.

Our Comp Cams XR282HR roller cam was timed in with the intake centerline at 104 degrees ATDC. With its 110 LCA, that works out to be 6 degrees advanced.

What you see here is a porting job done by a rank beginner. These EQ23 heads are about as easy as it gets to port for pro results. They flow great out of the box and even better with just a basic port job. We equipped our heads with the least expensive of Ferrea's valves.

The EQ heads showed good flow, good port velocity, and good swirl-all the ingredients for good output. And that is just what they delivered.

As with many times in the past, we built a successful high-rpm roller valvetrain around a Comp beehive spring. With minimal poundage to minimize roller collapse, these springs allowed the engine to go to its 6,500 redline flawlessly.

Here is our Zex perimeter spray nitrous plate in position. Note that the opening at the manifold face does not quite match. Our first job was to match the manifold to the plate and tidy up the runner-to-plenum junctions. The next job was to port-match this intake to the EQ23 heads.

For carburetion, a BG 750 Road Demon carb was chosen because annular disharge boosters generally produce the best results on a nitrous engine. For ignition, we used a Pertonix HEI and ACCEL plug cables.

The finished engine complete with the March serpentine belt system looked really sharp. The Performance Distributors alternator is a special that delivers high current at idle; ideal for a nitrous motor's amperage demands.

Doug Aitken and Dusty Kennett ready our 350 to do battle with the dyno. Just out of sight behind Doug is one of the pair of Flowmaster 4-inch mufflers we used.

The Zex perimeter plate system brought the power on strong and smooth. With the 150hp jetting, gains of up to 180 hp were seen.

Peaks of 438 lb-ft and 466 hp were recorded, but the real proof of this engine's street capability can be seen from its torque at 2,200 rpm. This was as low as the dyno would pull it down.

Our 350 small block was initially built to be driver friendly, but after a suggestion from Trick Flow Specialties, our Chevy 350 will brave a Magnacharger supercharger that would add over 100 hp and torque. - Super Chevy Magazine » Read More